SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3f416817a85859e6e573688adeb7c38f36442a9c9ddaf78d9043f201225eee' 
  AND token = 'G+o5MHp9NwcsCOrjcZSG1Y+4hu/juU18z9R8FwVum68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}